Detection and Identification of Aster Yellows Phytoplasma Associated with Lipstick Yellow Frond Disease in Malaysia

Yellowing symptoms similar to coconut yellow decline phytoplasma disease were observed on lipstick palms (Cyrtostachys renda) in Selangor state, Malaysia. Typical symptoms were yellowing, light green fronds, gradual collapse of older fronds and decline in growth. Polymerase chain reaction assay was employed to detect phytoplasma in symptomatic lipstick palms. Extracted DNA was amplified from symptomatic lipstick palms by PCR using phytoplasma‐universal primer pair P1/P7 followed by R16F2n/R16R2. Phytoplasma presence was confirmed, and the 1250 bp products were cloned and sequenced. Sequence analysis indicated that the phytoplasmas associated with lipstick yellow frond disease were isolates of ‘Candidatus Phytoplasma asteris’ belonging to the 16SrI group. Virtual RFLP analysis of the resulting profiles revealed that these palm‐infecting phytoplasmas belong to subgroup 16SrI‐B and a possibly new 16SrI‐subgroup. This is the first report of lipstick palm as a new host of aster yellows phytoplasma (16SrI) in Malaysia and worldwide.     

The effect of caffeine on prostaglandin output from the perfused mesenteric vascular bed of the rat

Caffeine significantly (p < 0.05) increased the output of prostacyclin (PGI₂) from the perfused rat mesenteric vascular bed. The outputs of PGE₂ and PGF_2α were also increased by caffeine. This stimulatory response to caffeine did not show rapid desensitization. Ryanodine also increased PG output, suggesting that caffeine may be acting via the stimulation of a ryanodine receptor. The increased production of a vasodilator such as PGI₂ from blood vessels following exposure to caffeine may explain why caffeine has a beneficial effect in angina.     

First Report of Phytoplasma (16SrI) Associated with Yellow Decline Disease of Royal Palms [Roystonea regia (Kunth) O. F. Cook] in Malaysia

Royal Palms (Roystonea regia) with symptoms such as severe chlorosis, stunting, collapse of older fronds and general decline were observed in the state of Selangor, Malaysia. Using polymerase chain reaction (PCR) amplification with phytoplasma universal primer pair P1/P7 followed by R16F2N/R16R2 and fU5/rU3 as nested PCR primer pairs, all symptomatic plants tested positively for phytoplasma. Results of phylogenetic and virtual RFLP analysis of the 16S rRNA gene sequences revealed that the phytoplasma associated with Royal Palm yellow decline (RYD) was an isolate of ‘Candidatus Phytoplasma asteris’ belonging to a new 16SrI‐subgroup. These results show that Roystonea regia is a new host for the aster yellows phytoplasma (16SrI). This is the first report on the presence of 16SrI phytoplasma on Royal Palm trees in Malaysia.     

Modulation of force induced by pH in the guinea-pig uterus examined at two stages of the oestrous cycle

Changes in pH have a marked influence on uterine contractility. Changes in uterine pH occur during pregnancy and labour, when marked endocrine changes are occurring. As hormonal status can also influence contractility, this study investigated whether pH-induced modulation of uterine force in influenced by hormonal changes. The effects of altering intracellular and extracellular pH on uterine contractions were studied in guinea-pigs on day 7 (high progesterone) and day 15 (low progesterone) of the oestrous cycle. Resting values of pH were significantly more acidic on day 15 compared with day 7, and more force was produced on day 15. Changing external pH produced similar changes in intracellular pH and force on both days. External acidification was associated with a large increase in force. In contrast, intracellular acidification, at constant external pH, reduced force. In conclusion, the stage of the oestrous cycle has a large effect on resting pH in the myometrium but only small effects on the pH-induced modulation of force, and the link between pH and force is complex.     

Semi-Analytical Solution for Solitary Waves in a Dissipative Suspension of Metallic Nanoparticles

Plasmonics - The semi-analytical solution for the soliton propagation in a suspension consisting of spherical metallic nanoparticles is studied. Considering the impact of imaginary part of...